The River Dearne South Yorkshire, England flows roughly east for more than 30 kilometres (19 mi), from its source just inside West Yorkshire. It flows through Denby Dale, Clayton West, Darton, Barnsley, Darfield, Wath upon Dearne, Bolton on Dearne, Adwick upon Dearne and Mexborough to its confluence with the River Don at Denaby Main. Its main tributary is the River Dove, which joins it at Darfield. The river was one of those affected by the 2007 United Kingdom floods.